Produce cleaning article containing potassium oleate

ABSTRACT

Basic cleaning compositions using toxicologically-acceptable ingredients for cleaning fruits and vegetables are provided. Clear liquid formulations comprising oleate, alcohol ethoxylates and buffers are sprayed onto apples, lettuce and the like to remove soil and unwanted deposits.

TECHNICAL FIELD

The present invention relates to methods for removing dirt and otherunwanted residues from produce, e.g., fruits and vegetables, which isintended for ingestion by humans or lower animals and to detersivecompositions, especially in liquid form, which are especially suitablefor practicing said methods.

BACKGROUND OF THE INVENTION

It is well-known and appreciated by consumers that fruits and vegetablesshould be thoroughly washed prior to ingestion in order to remove soilsand other unwanted residues which may be undesirably clinging to thesurfaces thereof. In addition, some consumers wish to remove theartificial "waxy" coatings which may be applied to some fruits to retardmoisture loss for increased storage life and to enhance theirappearance. It has been estimated that 95% of consumers recognize theneed for thorough washing but, ordinarily, only use tap water for thispurpose. On the order of 5% of those consumers who do wash theirvegetables use a household cleaner, typically a liquid dishwashingproduct, to help ensure cleanliness. However, dishwashing products arenot specifically intended for such use, inasmuch as they are usuallydesigned to provide high, persistent suds which makes them inconvenientto remove from the fruits or vegetables which have been washedtherewith. It will also be appreciated that the formulation of trulyeffective compositions, especially those which can be used safely byindividual consumers, for washing fruits and vegetables presents aunique problem to the formulator, inasmuch as many an-disclosed cleaningingredients would, presumably, not be desirable for use in directcontact with foods where they might not be fully removed.

Moreover, it would be especially desirable to provide effective,toxicologically-acceptable cleaning compositions for fruits andvegetables in the form of substantially low-sudsing liquid solutionswhich are clear or which have only minimal haziness. Liquid solutionsare convenient for the user, since they can be applied directly tosoiled fruits and vegetables, followed by rinsing in tap water. Theclarity of the liquids connotes cleanliness to the user and is thushighly desirable. Low sudsing is an important attribute so that removalof the solution by rinsing is achieved quickly and easily. It would alsobe of advantage if such compositions could be provided in the form ofconcentrates, which could be diluted by the consumer before use and/orapplied to the fruits and vegetables as a direct spray-on.

Unfortunately, many toxicologically-acceptable cleaning ingredients donot meet the aforesaid requirements for clear, low-sudsing, dilutableliquid products. Many detersive surfactants form cloudy or even opaquesuspensions in water. Of course, many surfactants are specificallydesigned to be high sudsing. Still others form relatively intractablephases in their concentrated form.

It has now been discovered that certain nonionic surfactants, properlyformulated with oleic acid or water-soluble oleate or laurate salts andother ingredients can provide liquid compositions having the desiredproperties described above. It has been discovered that preferredcompositions can be formulated in the acid pH range and have a desirableclean, "non-soapy" feel to the user's hands. Alternatively, certaincompositions can be formulated in the basic pH range. Even when suchbasic compositions do have a soapy feel, they are preferred over theacidic compositions herein for removing artificial waxy coatings,especially from fruit such as apples. However, the invention alsocomprises basic compositions having less soapy feel.

BACKGROUND ART

The use and selection of cleaning ingredients for the purpose of washingfruits and vegetables is described by the United States Code of FederalRegulations, Title 21, Section 173.315: "Ingredients for use in washingor lye peeling of fruits and vegetables". These regulations restrict theingredients that may be used for direct contact with food to thosedescribed as "generally regarded as safe" (GRAS), and a few otherselected ingredients. These sections also provide certain limitations onthe amount of material that can be used in a given context.

Among these ingredients, the experienced formulator will find only a fewingredients which can provide effective cleaning of hydrophobicresidues, such as waxes, oils, or man-made chemical residues such aspesticides. It is recognized that these types of residues are removedmost readily by surface active ingredients in water, or by organicsolvents largely in the absence of water. Other types of soils,especially particulate insoluble soils that do not readily disperse inwater, are effectively removed by surface active materials in water,especially when aided by complex anionic salts, such as citrates(polycarboxylates), or polyphosphate salts.

Within this limited group of ingredients the range of effective cleaningcompositions well suited to the task of cleaning fruits and vegetables,especially as practiced by individual consumers, have not beenpreviously described. It is desirable to formulate liquid compositionswhich are amenable to either direct application to produce, preferablyby spray application, or could be provided in suitable concentrated formto allow convenient dilution in a bowl or sink of water for washing ofproduce by immersion. Further, it is desirable the compositions are lowsudsing, and easily rinsed, without leaving residue. Preferredcompositions should be mild to the hands, especially for directapplication.

Food Chemical News, Inc., 1991, p. 334.1, reports that PEG 200-9500 hasbeen cleared under §178.3750 as a component in articles for use incontact with food (Fed. Register, Oct. 15, 1968). Nonetheless, forwashing produce, polyethylene glycol should be affirmed as GRAS.

SUMMARY OF THE INVENTION

The present invention encompasses methods for cleaning produce,especially fruits and vegetables, (and compositions, as disclosedhereinafter, for practicing said methods) at either an acidic pH, orbasic pH. The present invention comprises several aspects including:

I. A method for cleaning produce comprising contacting the surfaces ofsaid produce by direct application of an aqueous cleaning solutiontypically comprising:

(a) from about 0.01% to about 15% of C₈ -C₁₈ fatty acid, and preferablyless than about one eighth of the amount of nonionic surfactant in anacidic product;

(b) optionally, except that it is required when the pH is less thanabout 5.5, from about 0.1% to about 4% by weight of nonionic surfactant,especially ethoxylated/propoxylated adducts of aliphatic C₁₂₋₁₈alcohols;

(c) optionally, from about 0.1% to about 4% by weight of organicpolycarboxylic acid, preferably citric acid;

(d) optionally, up to about 0.2% by weight of an acid-stable anionicsurfactant such as the alkali or alkaline earth salts of dodecylbenzenesulfonate;

(e) optionally, a toxicologically-acceptable acidic buffer, other thansaid polycarboxylic acid and/or said fatty acid, sufficient to maintainthe desired pH;

(f) optionally, a toxicologically-acceptable basic buffer such aspotassium and/or sodium salts of carbonate and/or bicarbonate;

(g) optionally, a toxicologically-acceptable preservative; and

(h) the balance comprising an aqueous carrier selected from water and,optionally, low molecular weight, toxicologically-acceptable organicsolvent such as ethanol, glycerol, etc.;

wherein said aqueous solution has a pH either in the range of from about2.5 to about 5.5, preferably about 4, or in the range of 9.5 or greater,and preferably employs potassium carbonate as buffer (f) to provide a pHof about 11, said composition preferably being essentially free of anymaterial that is not toxicologically acceptable.

I(A) The inventions disclosed herein can preferably encompass a methodfor cleaning produce, e.g., fruits and vegetables, at an acidic pHcomprising contacting the surfaces of said produce by direct applicationwith an aqueous cleaning solution comprising:

(a) from about 0.1% to about 4% by weight of nonionic surfactant,preferably non-nitrogen containing nonionic detergent surfactant,especially ethoxylated/propoxylated adducts of aliphatic C₁₂₋₁₈alcohols;

(b) from about 0.01% to about 0.4% by weight of oleic acid, the ratio ofnonionic detergent surfactant to oleic acid being more than about 8:1;

(c) from about 0.1% to about 1.5% by weight of organic, preferablynaturally derived, organic polycarboxylic acid, e.g., citric acid;

(d) optionally, a toxicologically-acceptable acidic buffer, especiallypotassium hydrogen citrate, sufficient to maintain the desired pH;

(e) optionally, up to about 0.2% by weight of an acid-stable anionicsurfactant such as the alkali or alkaline earth salts of dodecylbenzenesulfonate;

(f) optionally, a toxicologically-acceptable preservative; and

(g) the balance comprising an aqueous carrier;

wherein said aqueous solution has a pH in the range of from about 2.5 toabout 5.5, preferably about 4.

I(B) The inventions disclosed herein can also preferably encompass amethod for cleaning fruits and vegetables at a basic pH, comprisingcontacting the surfaces of said fruits and vegetables with an aqueouscleaning solution comprising:

(a) optionally, from about 0.1% to about 4% by weight of nonionicsurfactant, especially ethoxylated/propoxylated adducts of aliphaticC₁₂₋₁₈ alcohols;

(b) from about 0.1% to about 15% by weight of a member selected from thegroup consisting of sodium or potassium oleate (preferred) or from about0.5% to 10% by weight of sodium or potassium laurate;

(c) optionally, but preferably, from about 0.2% to about 4% by weight ofpotassium and/or sodium polycarboxylate, having detergent buildingcapability and preferably being derived from natural sources, such aspotassium and/or sodium citrate, as a dispersant for particulate soils;

(d) optionally, a toxicologically-acceptable basic buffer such aspotassium carbonate; and

(e) the balance comprising an aqueous carrier selected form water andwater-ethanol;

wherein said aqueous cleaning solution has a pH of 9.5 or greater, andpreferably employs carbonate salt, or salts, as buffer (d) to provide apH of about 11 to about 12.5.

I(C) The inventions herein can also encompass a more specific method forcleaning fruits and vegetables at a basic pH, preferably more than about9.5, comprising contacting the surfaces of said fruits and vegetableswith an aqueous cleaning solution comprising potassium oleate,preferably at a level of more than about 0.5%. Potassium oleate is mild,rinses well, has minimal odor, is effective in removing unwantedmaterials, especially wax, from apples, does not oversuds, and is verysafe, even when the composition is misused and the vegetable, or fruit,etc., is not completely rinsed. Therefore, it is a uniquely preferredsurfactant for use in cleaning food materials like vegetables andfruits. The potassium cation is much more useful than the sodium cationsince the potassium oleate is quite soluble whereas the sodium oleatetends to form a less soluble soap, especially at low temperatures.

I(D) Another preferred, concentrated, alkaline method for cleaningproduce comprises contacting the surfaces of produce with a cleaningsolution containing from about 0.5% to about 15%, preferably from about0.75% to about 8%, more preferably from about 1% to about 5%, detergentsurfactant, preferably one that is GRAS, and more preferably said oleatesurfactant said cleaning solution having a pH of from about 8 to about12.5, preferably from about 9.5 to about 12.3, especially when thedetergent surfactant is a soap such as the said oleate, more preferablyfrom about 11 to about 12. Such compositions when used in an effectiveamount to clean apples coated with wax, will provide effective removalof the wax. Removal of wax from apples is one of the most difficultcleaning tasks and therefore is indicative of overall superiorperformance.

I(E) Yet another preferred variation in the above methods for cleaningproduce involves placing said cleaning solutions in a spray container toprovide a spray of said solution to distribute the said solution, orsolutions, over the surfaces of the produce while utilizing only aminimum amount of the cleaning solution and minimizing the exposure ofthe remaining solution to the atmosphere, where the solution is morelikely to be contaminated and/or exposed to oxygen, both of which tendto cause undesirable changes in the solutions from aesthetic and/orperformance considerations. In such spray processes, there is only needfor a relatively small amount of material in the package, and forindividual consumer use, this is desirable, since some consumers willnot be able to manipulate large weights. For consumer usage, typically,the container will contain no more than about two gallons (about fourliters), especially when the container is a spray container, even onethat has a tube that permits the spray device to be manipulated whilethe bulk container remains in place. Preferably such spray containerscontain about one liter, or less, of cleaning solution.

II. The invention also encompasses acidic and basic cleaningcompositions in both concentrated and dilute forms, especially adaptedfor practicing said methods. (In the following disclosure, the loweramounts of the specified ingredients denote the dilute forms of thecompositions herein and the higher amounts denote the concentrated formswhich are typically diluted by a factor of from about 2 to about 3.)Such compositions include the following.

II.(A) A composition for cleaning fruits and vegetables at an acidic pH,comprising:

(a) from about 0.1% to about 7.5%, preferably from about 0.3% to about4.5%, by weight of nonionic surfactant, as described above;

(b) from about 0.01% to about 0.75%, preferably from about 0.1% to about0.5%, by weight of oleic acid, the ratio of oleic acid to nonionicdetergent

surfactant being less than about 1:8;

(c) from about 0.1% to about 7.5%, preferably from about 0.3% to about4.5%, by weight of organic polycarboxylic acid, preferably citric acid;

(d) optionally, a toxicologically-acceptable acidic buffer;

(e) optionally, a toxicologically-acceptable preservative; and

(f) the balance comprising an aqueous carrier;

wherein said composition has a pH in the range of from about 2.5 toabout 5.5.

Preferably, the acidic compositions herein contain from about 0.5% toabout 3.0% by weight of potassium citrate as the acidic buffer (d) andhave a pH of about 4. Optionally, such compositions can contain up toabout 1%, preferably about 0.2%, by weight of an acid-stable anionicsurfactant, as described above.

II.(B) A composition for cleaning fruits and vegetables at a basic pH,comprising:

(a) optionally, from about 0.1% to about 4%, preferably about 0.3% toabout 1.0%, by weight of nonionic surfactant as described above;

(b) from about 0.1% to about 15%, preferably from about 1% to about 5%,by weight of a member selected from the group consisting of sodium orpotassium oleate (preferred), sodium or potassium laurate, or mixturesthereof;

(c) from about 0.2% to about 4% by weight of polycarboxylic acid salt,especially potassium hydrogen citrate;

(d) optionally, a toxicologically-acceptable basic buffer; and

(e) the balance comprising an aqueous carrier selected from water andwater-ethanol;

wherein said composition has a pH of 9.5 or greater.

Preferably, the basic compositions herein contain from about 0.5% toabout 1.5% by weight of potassium and/or sodium carbonate buffer andhave a pH of about 11.5.

II.(C) Preferred compositions for use herein in a concentrated alkalinemethod contain from about 0.1% to about 15%, preferably from about 0.5%to about 8%, more preferably from about 1% to about 5%, detergentsurfactant, preferably one that is GRAS, and have a pH of from about 8to about 12.5, preferably from about 9 to about 12.3, more preferablyfrom about 11 to about 12. Such compositions when used in an effectiveamount to clean apples coated with wax, will provide effective removalof the wax. Removal of wax from apples is one of the most difficultcleaning tasks and therefore is indicative of overall superiorperformance.

II.(D) The present invention also encompasses detersive compositionswith an improved tactile impression which are especially adapted forcleaning fruits and vegetables, comprising:

(a) at least about 0.1%, preferably from about 0.5% to about 8%, mostpreferably from about 1% to about 5%, by weight, of a C₁₂ -C₁₈ fattyacid or salt thereof;

(b) at least about 0.05%, preferably from about 0.1% to about 10%, mostpreferably from about 0.25% to about 3.0%, by weight, of a water-solublepolyethylene glycol having a molecular weight of about 200, or higher;

(c) a water or water-ethanol fluid carrier, said composition having abasic pH. The balance of the composition can comprise various optionaladjunct materials, pH-adjusting agents, perfumes or essences,preservatives and the like.

In a preferred mode, component (b) has a molecular weight in the rangefrom about 400 to about 9500.

Typical compositions herein are wherein component (a) is potassiumoleate, and wherein the weight ratio of(a):(b) is in the range fromabout 1:2 to about 15:1.

The compositions having improved tactile impression are typicallyformulated in the basic pH range, preferably from about pH 9.5 to aboutpH 12.3. Preferred compositions have a viscosity at room temperature ofless than about 100 centipoise, preferably less than about 50 centipoisefor sprayable compositions.

II.(E) Preferred compositions for use herein contain only materials thatare GRAS to protect against possible misuse by the consumer.Traditionally, most suggestions for cleaning of fruits and/or vegetableshave contemplated a commercial scale where there is typically morecontrol over the conditions, especially the amount and thoroughness ofrinsing. The present invention, especially the methods involving use ofhand held trigger activated spray means are primarily/solely suitablefor use by individual consumers so that it is essential that extrasafety be built into the product. Failure to rinse thoroughly aftercleaning is less of a concern if all of the ingredients are GRAS. Thisis especially important when concentrated basic compositions suitablefor removal of wax from apples are used. The larger amounts of materialsneeded for removal of wax create an heretofore unknown level of risk forthe individual consumers, many of whom are not likely to read, orfollow, instructions which would permit safe use of non-GRAS materials.

The ingredients in the above compositions are preferably selected andused in proportions which provide substantially clear compositions.Substantially clear includes only minimal haziness, and preferably thecompositions are completely clear. The ingredients are also selected tohave minimal odor, both initially and after storage. The lack of odor isespecially important in compositions for use on food. The compositionspreferably have a viscosity that is more than about 10 centipoise,preferably more than about 50 centipoise when at rest, but thin undershear to permit easy dispensing, especially from spray containers.

Below pH about 9.7, the compositions can exhibit some objectionablefatty acid odor. Even at the optimal pH's above 11, some odor canpersist. In order to mask this odor, the compositions can contain aperfume or essence ingredient. Especially preferred for this use areterpenes derived from citrus fruit, e.g., oranges, lemons, limes,grapefruits, tangerines, tangelos, etc.

All documents cited are incorporated herein by reference.

DETAILED DESCRIPTION OF THE INVENTION

The following toxicologically-acceptable ingredients are used in thepreparation of the preferred compositions herein. By"toxicologically-acceptable" is meant that any residues from theingredients of the compositions which may remain on the fruits orvegetables cleansed therewith are safe for ingestion by humans and loweranimals.

Nonionic Surfactant--The nonionic surfactant is preferably selected frommaterials known well-known in the art, such as alkylene oxide (ethyleneoxide or propylene oxide) adducts of C₁₀₋₁₈ aliphatic alcohols or acids,C₁₀₋₁₈ aliphatic alcohol adducts of glucose (alkyl polyglucosides). Thespecific nonionic surfactant selected ideally has ahydrophilic-lipophilic balance (HLB) greater than about 10, and a cloudpoint above about 35° C. in the composition. The United States Code ofFederal Regulations (CFR) specifically describes an ethyleneoxide/propylene oxide adduct of C12-18 aliphatic alcohol of molecularweight of about 800. Such a material is available as PLURAFAC RA-20(BASF).

It is to be appreciated that in the acidic compositions herein, thealkoxylated alcohol functions substantially as a cleansing agent,whereas in the basic compositions the alkoxylated alcohol functionsmainly as a dispersant for any soap curd which may form during thecleansing operation. Further, it is recognized that the selection ofnon-nitrogen containing nonionics can minimize the possibility ofmicrobial growth in the dilute surfactant compositions.

Fatty Acid and/or Salts Thereof--The acidic compositions herein areformulated using an unsaturated fatty acid; oleic acid is preferred andconvenient for this use. However, the particular oleic acid that isselected should preferably be low in polyunsaturates, e.g., contain lessthan about 10%, preferably less than about 7%, more preferably less thanabout 5% and will typically have an Iodine Value (IV) of from about 70to about 100, preferably from about 83 to about 95, more preferably fromabout 85 to about 90. Polyunsaturated fatty acids are not preferredherein, due to odor problems. However, this is primarily from aestheticconsiderations since such acids are effective in cleaning. The amount ofpolyunsaturated fatty acids should be less than about 8%, preferably 0%.The amount of polyunsaturated fatty acids with more than about twodouble bonds should be less than about 1%, preferably 0%. Saturatedfatty acids are unacceptable as they have limited solubility for longerchainlength materials (≧C₁₂), or have unacceptable odor (≦C₁₄). Forexample, stearic and/or tallow fatty acids soaps, even potassium soaps,do not have enough solubility at room temperature, where most producecleaning is done by individual consumers, to formulate even compositionscontaining the minimum of about 0.1% soap required for acceptablecleaning. Other specific solubilizing surfactants in higher proportionswould be required to solubilize these saturated fatty acids. Pamolyn 100FGK oleic acid is a good example of a suitable commercial fatty acid.

For the acidic compositions, other low HLB (<6) nonionics can besubstituted, such as monoglycerides, but these are less preferred thanoleic acid. The purpose of these materials is to provide acceptablecleaning with low sudsing to the compositions. Preferably, in the acidiccompositions the oleic acid is used in an amount that is less than about1:8 (about 12%) by weight of the nonionic surfactant. For the basiccompositions, sodium oleate or sodium laurate can be employed, but onlysodium oleate is described as GRAS on the CFR. The fatty acid (or saltthereof) functions both to provide a cleansing action and to dampensudsing. In the acidic formulation, the pH of very dilute mixtures iskept below 7.0 by citric acid to prevent formation of cloudiness.

Polyethlene Glycol--The water-soluble polyethylene glycol polymer (PEG)employed herein is the known article of commerce and is available undera variety of trade names, of which CARBOWAX (Union Carbide Corporation)is exemplary. PEG's in the average molecular weight range of from about200 to about 20,000 can be used herein, and PEG as CARBOWAX in theaverage molecular weight range of at least about 400, typically 400 toabout 9500, is convenient and preferred. As disclosed above, thecompositions herein will comprise at least about 0.05%, by weight, ofthe PEG and will typically comprise from about 0.1% to about 10%, byweight, of PEG. The amounts used can vary with the molecular weight ofthe PEG, the amount of oleate or other fatty acid used in thecomposition, the desired viscosity of the composition, and like factorswithin the discretion of the formulator. The following Table 1illustrates the variation in viscosity which can be effected usingvarious levels of PEG and varying PEG molecular weights in a liquidcomposition (Control) comprising 3% potassium oleate. Table 1 alsoillustrates the effect of sodium benzoate (Bz) on viscosity.

                  TABLE 1    ______________________________________                     Viscosity   Viscosity                     (cP* as made)                                 (cP* as made)    Composition      72° F. (22° C.)                                 43° F. (6° C.)    ______________________________________    Control (no PEG) 7           110    Control + 0.674% Bz                     23          1000    Control + 0.118% Bz                     7           159    Control + 0.1% PEG 400                     5           36    Control + 0.5% PEG 400                     2           17    Control + 0.1% PEG 8000                     5           23    Control + 0.5% PEG 8000                     8           4    ______________________________________     *Viscosity in centipoise as measured using Brookfield LVTD #2 spindle, 60     rpm at the designated temperature.

In a typical mode, the preferred compositions herein that have animproved tactile impression will comprise oleate:PEG weight ratios inthe range from about 1:2 to about 15:1, preferably from about 1:1 toabout 10:1.

Tactile Impression--The compositions herein which contain thepolyethylene glycol are characterized not only by their excellentcleaning performance and sudsing/rinsability properties, but also bytheir improved viscosity properties and improved "feel". While, asdisclosed above, the improved viscosities of the compositions herein arereadily demonstrated quantitatively using standard measurementtechniques, the improved feel of the compositions which come intocontact with the user's hands is a qualitative tactile impression.However, this improved, "non-slippery", "non-soapy" improvement in skinfeel can be demonstrated by rubbing Test (PEG-containing) and Control(no PEG) compositions on the hands or inner forearms of volunteergraders. Even in such rudimentary tests, the graders can readilydistinguish the improved tactile impression of the compositions made inaccordance with this invention.

Optional Surfactants--Optionally, acid or base stable anionicsurfactants can be employed, as allowed by the United States Code ofFederal Regulations, Title 21, Section 173.315. Preferred are salts ofdodecylbenzene sulfonate, typically at levels up to 0.2%. Also describedin the CFR are phosphate esters of ethylene and/or ethylene/propyleneoxide adducts of aliphatic alcohols, dioctyl sulfosuccinate, or2-ethylhexyl sulfate, typically but these materials surlier from lack ofstability at either acid or basic conditions.

Sequestrant/builder--The organic polycarboxylic acid, or salt thereof,e.g., citric acid, is used as a sequestrant/builder in the acidiccompositions herein or sodium and/or potassium citrate as used in thebasic compositions herein are standard items of commerce. Other organicpoly carboxylic acids, especially those that are GRAS, such as tartaric,malic, etc. acids, can also be used. When formulating the basicformulations herein, it is preferred to use the potassium salt, ascompared with the sodium salt, to provide ease of formulatability.Complex phosphates can also be used, but are generally avoided due toregulatory considerations.

Buffer--Toxicologically-acceptable acidic or basic buffers can be usedin the compositions herein to maintain product pH in the acid or baserange. For ease of formulatability, it is highly preferred that suchacidic and basic buffers be in their potassium salt form. Citric acid isa preferred acid pH buffer, and in the basic pH systems, potassiumcitrate is a preferred dispersant for particulate soils. Potassiumcarbonate is a convenient and preferred basic pH buffer. Sodiumbicarbonate is a highly desirable material to add to the compositions ofthis invention as a part of the buffering system since it is readilyavailable as baking soda in food grade and is therefore relativelyinexpensive, while providing a highly desirable purity to thecomposition. Compositions formulated with a mixture of potassium andsodium cations in molar ratios of from about 1:1 to about 10:1,preferably from about 2:1 to about 8:1, more preferably from about 4:1to about 5:1 potassium to sodium, e.g., as provided by mixtures ofpotassium hydroxide (hydrate) and sodium bicarbonate, have desirablerheological properties. The compositions are thick, so as to cling tothe fruit or vegetable until spread, but are readily dispensed, e.g., bymeans of a spray device, either aerosol or finger-activated pump. Thelevels and identities of the ingredients are adjusted to provideproducts having the desired viscosities as set forth herein, e.g., morethan about 5, preferably more than about 10, more preferably more thanabout 50 centipoise when at rest, and less than about 150, preferablyless than about 100, more preferably less than about 50 centipoise undershear of ≧˜1000 sec⁻¹.

The ability of the preferred compositions containing mixtures of bothsodium and potassium cations to shear thin is important to promote easydispensing, especially when the compositions are sprayed, whilemaintaining the ability to be thick, cling, and delay run off afterbeing applied to the produce.

The pH is preferably not greater than about 12.5, and especially doesnot contain large amounts of buffer at higher pHs for consumer safety,especially when the compositions are sprayed.

Preservative--The strategy of formulating the present compositions ateither high or low pH is based on the reduced tendency for biologicalgrowth of contaminants, such as bacteria, fungi, or molds, at eitherhigh pH (>9) or low pH (<5). At neutral pH, an increased reliance onpreservatives is required to insure the lack of biological growththrough contamination in making or in use. The acidic compositionsherein do preferably contain a minimal amount, typically from about0.01% to about 0.2% by weight, of a toxicologically-acceptablepreservative in order to prevent the growth of fungi, bacteria or likein the product on storage. Standard food-grade preservatives such aspotassium sorbate/sorbic acid and/or sodium benzoate/benzoic acid, ormixtures thereof, are suitable for such purposes. For example, fromabout 0.01% to about 0.2% of benzoic acid or its sodium or potassiumsalts can be used. In general, the basic pH compositions herein do notrequire a preservative, although one can be added if desired.

Antioxidants The use of commercial oleic acid, or oleate salts, can becomplicated by development of off-odors and/or yellowing of thecompositions in which they appear. These undesirable properties arebelieved to be caused by complex side reactions initiated by thereaction of oxygen with primarily the polyunsaturated components of thefatty acid stock. These results can be avoided, or minimized, byavoiding contact with air, or by controlling the quality of the fattyacid stock so that the amount and type of polyunsaturates are minimizedas described above, and/or by the addition of antioxidants.

It has been found, that the addition of tocopherols (e.g., Vitamin E, ortocopherol acetates) in alkaline formulations is advantageous, as theydo not degrade, nor do they impart a strong color. They inhibit thedevelopment of off-odors for extended periods of time so that the needfor masking scents is minimized, or eliminated, particularly for oleicacid stocks of high quality, as described above. The use of butylatedphenols, such as BHT and BHA is also useful, but their effectivenessappears more limited and they can impart stronger colors to thecompositions. Other food grade antioxidants such as Vitamin C andsulfites, are desirable to prevent deterioration of the compositions bythe action of oxygen, but care must be taken since vitamin C can suffercolor degradation and sulfites can cause odor problems. Sulfites alsohave been the target of potential health concerns. In acidicformulations, vitamin C can be advantageous since its color degradationis less severe.

Fluid Carrier--The major proportion (typically, 90%-98%, by weight) ofthe compositions herein comprises water as the solubilizing carrier forthe ingredients. As noted in the Examples hereinafter, water-ethanol canalso be employed and is especially preferred when formulating basic pHcompositions herein. The ethanol level preferably should not exceed 2%in the solution used to clean the produce, to avoid an alcoholic odor,especially when spraying. Other compatible, water-soluble, low molecularweight solvents such as glycerol can also be used.

It has been discovered that for the acidic compositions (pH 5.5, andbelow) described herein, a unique non-slippery solution feel is impartedby the low pH compositions, especially at total levels of surfactantplus oleate below about 3%. Such characteristic appears to be unique tothese compositions, compared to comparable compositions at neutral orhigh pH. This solution feel is preferred for ease of handling and easyrinsing.

The compositions herein are preferably used by placing them in a packagecomprising either an aerosol container or a non-aerosol spray device"spray means." Said spray means is any of the manually activated,preferably "trigger-type," means for producing a spray of liquiddroplets as is known in the art. Typical spray means are disclosed inU.S. Pat. Nos.: 4,082,223, Nozawa, issued Apr. 4, 1978; 4,161,288,McKinney, issued Jul. 17, 1979; 4,558,821, Tada et al., issued Dec. 17,1985; 4,434,917, Saito et al., issued Mar. 6, 1984; and 4,819,835,Tasaki, issued Apr. 11, 1989, all of said patents being incorporatedherein by reference. The spray bottle, or container can be any of theones commonly used for containing hard surface cleaner detergentcompositions. Examples of bottles are those in U.S. Pat. Nos. Des:244,991, Weekman et al., issued Jul. 12, 1977; and 275,078, Wassergordet al., issued Aug. 14, 1984, said patents being incorporated herein byreference.

The spray means herein can also include those that incorporate apropellant gas into the liquid and those that will foam even detergentcompositions having a viscosity of less than about 15 cps. The devicecan also be one that can be adjusted to either give a liquid spray or afoam. The spray means herein are typically those that act upon adiscrete amount of the composition itself, typically by means of apiston that displaces the composition and expels the composition througha nozzle to create a spray of thin liquid.

Preferred articles include the compositions herein that are suitable foruse in the processes described herein, in a package that can provide aspray. Such articles are not widely marketed. This is surprising in viewof the clear advantages for such products for use by individualconsumers. The typical use involves treating individual items ofproduce, which would make preparation of a "bath" wasteful.

In a preferred process for using the products described herein, andespecially those formulated to be used at full strength, the product issprayed onto the food product to be cleaned, rubbed, rinsed and/or wipedoff with a suitable material like cloth, sponge, a paper towel, etc.Surprisingly, the compositions and processes described herein,especially those that are alkaline, can provide effective disinfectancy.

All parts, percentages, and ratios herein are "by weight" unlessotherwise stated. All number values are approximate unless otherwisestated.

The following Examples illustrate the compositions and processes of thisinvention, but are not intended to be limiting thereof. The exemplifiedbasic liquid compositions can be prepared at pH 9.5-12.3 by dissolvingthe ingredients in water or water-ethanol using conventional mixingapparatus. In a convenient mode, water is placed in a mixing vessel.Potassium hydroxide, citric acid, the bicarbonate, glycerine (processingaid) and ethanol are added in the named sequence, with stirring. Theoleic acid is added with high shear and stirring is continued. The PEG(which can conveniently be predispersed in water) is then added. Theoptional perfume ingredients can be added any time after the oleic acidhas been dissolved in the mixture.

EXAMPLE I

A concentrated acidic cleaning composition is prepared by dissolving thefollowing ingredients in water.

    ______________________________________    Ingredient        % (wt.)    ______________________________________    PLURAFAC RA-20    4.5    Oleic acid        0.25    Citric acid       2.0    Potassium citrate 2.0    Potassium sorbate 0.1    Sodium benzoate   0.1    Water             Balance    ______________________________________     Product pH 4

In use, for example, the composition of Example I is diluted 3-fold withwater and sprayed onto soiled fruits and vegetables such as apples,grapes, peaches, potatoes, lettuce, tomatoes, celery, and the like, withlight scrubbing as may be required. After rinsing in tap water, thefruits and vegetables are cleansed and ready for use.

EXAMPLE II

A concentrated basic cleaning composition is as follows.

    ______________________________________    Ingredient        % (wt.)    ______________________________________    Sodium oleate     3.0    Potassium citrate 1.5    Potassium carbonate                      1.5    PLURAFAC RA-20    1.0    Ethanol           2.0    Water             Balance    ______________________________________     Product pH 11.5

The composition of Example II is prepared by adding oleic acid toethanol or ethanol/water, neutralizing with NaOH, and then dissolvingthe resulting solution with the balance of the ingredients in water.

In use, for example, the composition of Example III is diluted 2-foldwith water and sprayed onto soiled produce, e.g., fruits and vegetablessuch as apples, grapes, peaches, potatoes, lettuce, tomatoes, celery,and the like, with light scrubbing as may be required. After rinsing intap water, the fruits and vegetables are cleansed and ready for use.

EXAMPLE III

Liquid compositions suitable for direct application to fruits andvegetables, including by spray-on, are as follows:

    ______________________________________                   % (wt.)      % (wt.)    Ingredient     Composition A                                Composition B    ______________________________________    Oleic Acid     2.64*        1.32    Ethanol        2.0          2.0    Glycerol       2.0          2.0    PEG (avg. mol. wt.)                   0.5 (4600)   1.5 (8000)    KOH            1.49         1.23    KHCO.sub.3     0.65         0.65    Citric Acid    0.63         0.63    Oil Grapefruit Terpenes                   0.04         0.02    EX-5-fold    Water          Balance      Balance    ______________________________________     *Corresponds to 3% potassium oleate.

In-use, the compositions are applied through the commercial trigger-typespray device used with the commercial product CINCH® directly to soiledfruits and vegetables such as apples, grapes, peaches, potatoes,lettuce, tomatoes, celery, and the like, with light scrubbing as may berequired. After rinsing in tap water, the fruits and vegetables areready for use. The waxy materials commonly used to reduce water loss forextended storage life and to produce a sheen on apples can also beremoved by application of the compositions. An advantage of the consumercleaning produce is that materials serving a useful function, like waxon apples, are removed immediately before use so as to prolong theireffect as long as possible.

If desired, the compositions of Example III can be concentrated up toabout 5-fold by removal of a corresponding amount of water-ethanolsolvent. The concentrates are preferably diluted back to correspond to3%-5% potassium oleate prior to use in an immersion or spray-on cleaningoperation.

What is claimed is:
 1. A produce cleaning article comprising a spraycontainer containing a cleaning solution which consists essentiallyof:(a) from about 0.1% to about 5% by weight of potassium oleate; (b)optionally, from about 0.1% to about 4% by weight of a nonionicsurfactant; (c) optionally, from about 0.2% to about 4% by weight oforganic polycarboxylate detergency builder; (d) optionally, atoxicologically-acceptable basic buffer; and (e) the balance being wateror water-ethanol fluid, which has a pH of at least about 9.5 to about12.5, wherein said spray container comprises manually-activated,trigger-type, spray means.
 2. The article of claim 1 wherein saidpotassium oleate and said nonionic surfactant are generally regarded assafe.
 3. The article of claim 2 wherein said solution contains fromabout 0.75% to about 5% by weight of said potassium oleate.
 4. Thearticle of claim 3 wherein said solution contains from about 1% to about5% by weight of said potassium oleate.
 5. The article of claim 1 whereinsaid solution has a pH of from about 9.5 to about 12.3.